Renal allografts: prospective analysis of Doppler sonography.

Fifty-six consecutively transplanted renal allografts were prospectively evaluated with serial Doppler sonographic examinations. Thirty-eight episodes of transplant rejection in 32 patients (63% proved pathologically) and 24 episodes of acute tubular necrosis (ATN) in 24 patients were encountered. The Doppler spectral waveform was characterized by means of the pulsatility index (PI), systolic/diastolic ratio (SDR), diastolic/systolic ratio (SDR), diastolic/systolic ratio (DSR), and resistive index (RI). Accuracy was optimized with use of top normal values as follows: PI = 1.8, SDR = 4.0, DSR = 0.25, RI = 0.75. There were no significant differences in the indices for those patients undergoing rejection versus those with ATN. The sensitivity for predicting transplant rejection was adversely affected by the history of either ATN or a previous rejection episode in the same allograft. Comparison with concurrent radionuclide examinations revealed similar sensitivities for rejection with scintigraphy and sonography. Differentiation of ATN from rejection was more reliable with scintigraphy than with sonography.